1. Field of the Invention
The present invention relates generally to chain link fabrics and, more particularly, to an improved chain link fabric with flattened ends and a method and apparatus for forming the flattened ends of the fabric.
2. Description of the Related Art
It has been estimated that throughout the world, millions of square feet of chain link fabric are produced and sold annually. Recognizing the importance of providing effective and durable chain link fabric, the American Society for Testing and Materials (ASTM) has established minimum quality standards for both residential and commercial chain link fabric. Realizing that chain link fabric can be effective for various different applications, the fencing and chain link industry has developed many different types of chain link fabric. Each type of chain link fabric has specific features that provide additional advantages when the fabric is used for its intended purpose.
Typically, chain link fabric is used as a barrier. When it is used as a barrier, it is typically used with some type of support member, such as a fence frame, that holds the fabric in place. Also, chain link fabric commonly is used to control or prevent the movement of nearby objects. For example, chain link fabric often is used in land fills and mines, and on land to control rocks, boulders, and soil.
Traditionally, chain link fabric is produced using a weaving machine. A typical weaving machine continually feeds two strands of wire into a weaving blade and trough mechanism that bends and weaves the two wires together. The weaving blade and trough interweave the two wires by helically winding them to provide a continuous mesh, without knots or ties, except possibly at the edges of the finished fabric. After being woven together, the formed continuous links of chain link fabric are cut off at the edges, leaving sharp wire-end portions. How the edges of the fabric are finished is generally referred to as the selvage. Typically, the selvage is knuckled or barbed depending on the intended use of the chain link fabric. If a knuckled edge is desired, typically, an assembly on the weaving machine bends the sharp wire-end portions of the fabric over one another, forming a knuckle at the edge of the chain link fabric. Similarly, if a barbed edge is desired, typically, an assembly on the weaving machine twists the sharp wire-end portions creating a sharp barb at the edge of the chain link fabric.
Forming a chain link fabric having the characteristics, and using the method, described above has certain drawbacks. One such drawback is that knuckled or barbed ends are weak and easily can be crushed or bent out of place. When someone or something comes into contact with the barbed or knuckled ends of chain link fabric, the ends may be crushed or bent out of place. Either way, the damage may be so severe that the fabric must be repaired or replaced.
Additionally, if the ends of the fabric protrude because they have been bent out of place, the fabric has an undesirable, if not unsightly appearance. The protruding ends of the fabric are also more likely to cause injury because individuals passing by are more likely to come into contact with them. The protruding ends can poke individuals who do not notice them, causing serious injury.
Sometimes, individuals who encounter a fence will try to get around it by climbing it. The protruding ends of a damaged chain link fabric can poke an individual trying to climb the fence in a sensitive area, for example, the eye, or catch on to the individual's clothing as he is climbing the fence, causing the individual to fall and be seriously injured. The additional risk of injury and the undesirable appearance that results when the barbed and knuckled ends of the fabric are damaged can result in additional time being spent and expenses being incurred to repair or replace the damaged chain link fabric.
Another drawback of the chain link fabric described above, is the difficulty associated with shipping, installing, and removing it. Typically, after the fabric has been woven and the selvage has been formed, the fabric leaves the weaving machine and it is rolled into a compacted form that is useful for shipping. The chain link fabric is usually compacted by rolling the fabric so that the diamonds of the fabric collapse into each other to form a relatively tight and small roll of fabric. However, the knuckled or barbed ends of these compacted rolls usually become tangled in the rest of the chain link fabric, causing the ends to be bent out of place or pulled apart.
Alternatively, if the fabric is attached to a fence frame or other type of support member, when separate frames are placed close to one another the knuckled and barbed ends of the different chain link fabrics can get tangled together and pulled apart. The damaged ends of the fabric may require repair, resulting in additional time being spent and expenses being incurred. Additionally, individuals who install and repair the fabric are exposed to the additional risk of being seriously injured by the sharp barbed and knuckled ends that must be untangled, repaired, and installed.
Although there are known types of fence fabric, which might be categorized as having flattened end portions, these fabrics also have certain disadvantages. One such disadvantage is that many of these fabrics, such as gabion, are made of a very light gauge wire (typically 9 to 11 gage), which cannot be an effective permanent barrier and is more expensive to use. The flattened end portions of fabrics, other than gabion, typically are not strong enough to resist large forces, (e.g., an individual climbing onto the fabric) without bending or crushing. Even though a ¼″ rod is sometimes use to strengthen the fabric, the rod usually does not provide enough strength to allow the fabric to resist large forces. Typically, chain link fabrics are used in environments where a substantial number of people or animals are nearby. Some of these people or animals will exert a large force on the chain link fabric by trying to climb over it or go under it. Therefore, through regular use, these fabrics usually experience a large amount of force at some time during their useful life. As a result, these fabrics usually are crushed or bent when a large force is exerted on them. The bent or crushed fabric must then be repaired or replaced resulting in additional time being spent and expenses being incurred.
Yet another disadvantage associated with chain link fabrics that might be categorized as having flattened end portions is that they often have protrusions and sharp edges at the ends of the adjoined wire-end portions resulting from a straight cut that can cause serious injury. More specifically, the flattened end portions are typically butt welded together, i.e., the ends of the flattened end portions are aligned with one another, without overlapping, during the welding process, or lap welded together, i.e., the flattened end portions overlap one another during the welding process, in a manner that leaves sharp edges and protrusions that are dangerous. Over an extended period of time, these protrusions and sharp edges can result in serious injury to numerous individuals. This is especially true when the individuals nearby do not see the protrusions, or do not appreciate the harm that they can cause (e.g., harm to small children and young adults). Therefore, fabrics having sharp edges and protrusions create an increased risk of injury when they are located near schools or in other areas where large numbers of children likely are to be present.
Accordingly, there exists a need for an improved chain link fabric that has strong, flattened end portions configured to withstand large forces without bending or crushing, and does not pose a serious risk of injury to installers and others that come into contact with it. There also is a need for chain link fabric that quickly can be prepared for transportation and easily installed, and that has an improved aesthetic appearance that lasts. Additionally, there exists a need for a method and apparatus for efficiently making the flattened end portions of the improved chain link fabric. The present invention fulfills these needs.